Diabetes is a disease group which causes hyperglycemia due to absolute or relative lack of an insulin action. Because the persistence of hyperglycemia induces neuropathy, retinopathy, nephropathy, and atherosclerotic disease, prevention or treatment of diabetes is one of the important targets in the present medicine. Diabetes is divided into type 1 diabetes and type 2 diabetes depending on the pathogenic mechanism. Type 1 diabetes is a disease in which pancreatic β cells are destroyed by autoimmunity and disappeared, and is characterized in that the absolute lack of an insulin action. Thus, an insulin treatment is generally used. There are some types of diabetes such as Brittle type, in which control of insulin is difficult. Type 2 diabetes is characterized in that relative lack of an insulin action, and is caused by the complication of so-called metabolic syndrome. Thus, the main therapy is administering drugs for improvement of insulin resistance preventing an insulin action, or drugs for acceleration of insulin secretion from pancreatic β cells. The patients with type 2 diabetes in Europe and the United States have the insulin resistance as its main pathology, while the patients with type 2 diabetes in Japan additionally have exhaustion, depletion, and disappearance of pancreatic β cells. Therefore, in Japan, the therapy which replaces insulin is essential for both type 1 diabetes and type 2 diabetes.
Recently, transplantation of pancreatic islets are conducted. In some cases, withdrawal from insulin is observed, and in other cases in which withdrawal from insulin is not achieved, improvement in control of insulin is observed (Non-Patent Documents 1, 2 and 3). However, because a donor, which may be living or dead, is required for transplantation of pancreatic islets, its resource is restricted. In order to solve such problem, attempts to generate pancreatic islets have been made. Recently, it was reported that generation of pancreatic islets from ES cells was successful (Non-Patent Document 4). However, transplanting the insulin-secreting cells from these cells has not only the problem of HLA incompatibility but also the ethical problems, and has the possibility of existing a virus or antigen from an animal of a different species. Additionally, there is a limit to types and amounts of the established ES cells. Therefore, it is difficult to provide the insulin-secreting cells to all patients who require transplanting thereof.
If the insulin-secreting cell is the cell which can be obtained from autologous somatic stem cells, it is considered that there is no need to consider the problem of HLA incompatibility, and there are medical and social advantages rather than the ethical problems. However, it has not been reported that the generation of the pancreatic islets from somatic stem cells is successful.
Non-Patent Document 1: Shapiro A M et al., N Engl J Med. 2000 Jul. 27; 343(4): 289-90
Non-Patent Document 2: Ryan EA et al., Diabetes. 2005 July; 54(7): 2060-9
Non-Patent Document 3: Matsumoto S et al., Lancet. 2005 May 7-13; 365(9471): 1603-1604
Non-Patent Document 4: Segev H et al., Stem Cells 2004; 22: 265-274